Glee sources informed E! News that Lohan was a "total nightmare," showing up late after a long night out (her rep called it a "misunderstanding" about her call time) and rubbing early bird castmembers the wrong way.

Sure enough, E! News has learned that Lohan texted her rep right after work, telling him that she was so ahead of schedule today, she finished her shoots at 1 p.m.—three hours early!

And since Lohan was said to be a true professional last week, and yesterday's tardiness didn't hold up production, it sounds as if the ultimate result from the comebacking actress's guest appearance is going to be music to fans' ears.